This study will compare different ways of giving the drugs ganciclovir and valganciclovir to kidney or kidney and pancreas transplant recipients to determine if valganciclovir is providing similar protection against cytomegalovirus (CMV) compared with conventional therapy with ganciclovir. The reason for this comparison is that valganciclovir is better absorbed and has the advantage of once a day oral dosing. The pharmacokinetics of this drug has been studied in patients with HIV infection and CMV infection however, it has not been studied in kidney transplant patients. CMV is a serious viral infection occurring following organ transplant that can result in significant illness or death. To date 2 male kidney transplant patients (1 cadaveric and 1 living donor transplant) have enrolled. This study consists of four phases. Each phase or drug dose has been selected to mimic ganciclovir and valganciclovir use in the kidney transplant population. The first phase consists of serial blood sampling for ganciclovir blood levels after intravenous ganciclovir. The second phase consists of serial blood sampling for ganciclovir levels following oral valganciclovir at 900mg orally per day. These two phases will be compared for equivalency of drug levels and exposure. The third phase consists of serial blood levels following 450mg of oral valganclovir daily. The fourth phase consists of serial blood samples after oral ganciclovir 1 gram every 8 hours. The thrid and fourth phases will be compared for equivalency of drug levels and exposure. At this time, one subject has completed phase 1 and 2 and the second subject has completed phases 1 through 3. Since the blood samples will be pooled and processed after 7 patients have completed all 4 phases, there are no results available at this time. By characterizing the pharmacokinetics of valganciclovir in the kidney transplant population, it is hoped that appropriate dosing to prevent CMV disease and limit toxicity may be achieved. This research will also be useful as a foundation to study the pharmacokinetics of valganciclovir in transplant patients with compromised renal function.